Topical Medications for Atopic Dermatitis and Effects on Increasing Lymphoma Risks.

Atopic dermatitis is an immune-mediated skin condition that causes relapsing, pruritic skin lesions. Flares of this disease are often treated with topical corticosteroids; however, the use of these drugs can cause unwanted side effects, such as cutaneous atrophy and impaired wound healing. To minimize these common side effects, severe forms of this disease have been treated with topical calcineurin inhibitors, which previously had no known long-term side effects. Recently, there has been debate on the immunosuppressive effects of these drugs and whether chronic use could result in non-melanoma skin cancer. Systemic absorption of topical calcineurin inhibitors is extremely limited compared to oral formulation, although it is directly proportional to the total body surface area applied with medication. Patients with atopic dermatitis can have an increased risk of lymphoma, so it is hard to distinguish the causative factor, e.g., severe atopic dermatitis or being treated with calcineurin inhibitors. While inconclusive, the Food and Drug Administration recently issued a black box warning, and currently, topical calcineurin inhibitors are considered a second-line treatment. The present investigation reviews the findings of multiple studies conducted to determine if there is a link between the usage of topical calcineurin inhibitors and lymphoma.

Exploring the reasons why mothers do not breastfeed, to inform and enable better support.

Introduction: Infant and maternal breastfeeding benefits are well documented, globally. Despite efforts to increase global breastfeeding rates, the majority of high-income settings fall short of recommended targets. Breastfeeding rates in the UK are especially poor, and physiological difficulties (e.g., inverted nipples), fail to account for the observed breastfeeding intention-behaviour gap. Method: The current online study sought to investigate the infant feeding experiences of 624 UK formula feeding mothers, through open text survey responses. Results: A content analysis identified the following clusters of reasons for formula feeding: Feeding Attitudes, Feeding Problems, Mental Health, and Sharing the Load. Discussion: Feeding Attitudes explained a large percentage of reasons given for formula feeding. Recommendations are made to improve antenatal breastfeeding education and to develop an intervention with an aim to improve maternal breastfeeding attitudes and subsequent practice. Feeding Problems also explained a large portion of combination feeding and started but stopped infant feeding accounts. The current paper calls for more comprehensive and tailored antenatal breastfeeding education to refine practical breastfeeding skills necessary for successful breastfeeding establishment and maintenance. Mental Health explained relatively small coverage. Suggestions are therefore made to train mental health practitioners on infant feeding with an aim to provide more extensive support, which may serve to disrupt the bidirectional relationship between poor mental health and poor breastfeeding outcomes. Finally, Sharing the Load explained moderate coverage across never breastfed, combination fed, and started but stopped feeding groups. Recommendations are made, in light of these findings, to tighten workplace legislation to protect breastfeeding women.

Diastereoselective access to substituted oxetanes via hydrosilylation-iodocyclisation of homopropargylic alcohols.

The regio and stereoselective hydrosilylation of a variety of homopropargylic alcohols and their derivatives is described. The reaction is tolerant to a variety of sterically and electronically varied substrates, affording only the E-vinyl silane as a sole regioisomer. The application of the resultant vinyl silanes towards the diastereoselective synthesis of tetrasubstituted oxetanes is demonstrated.

Time to Post-Anesthesia Neurological Evaluation and Hemodynamic Stability in Carotid Endarterectomy Comparing Three General Anesthetic Techniques Targeted to a Preset Bispectral Index Value: A Pilot Study.

Carotid endarterectomy (CEA) has a 1-5% risk of periprocedural stroke. The ability to emerge patients from anesthesia quickly to detect neurological abnormalities immediately after surgery is vital in this patient population. The objective of this pilot study was to assess if any of three general anesthetic techniques for CEA are associated with a shorter time to a reliable postoperative neurological exam. Secondary objectives were to assess postoperative cognitive dysfunction (POCD), postoperative delirium (POD), and hemodynamic stability. Twenty-one patients undergoing CEA were enrolled and randomized to different combinations of inhalational and intravenous anesthesia: Group A: propofol, remifentanil, and desflurane; Group B: dexmedetomidine, remifentanil, and desflurane; Group C: remifentanil and desflurane. Anesthetic depth was titrated using a bispectral index (BIS) monitor to a goal of 50-60. Time was recorded from surgery end to first meaningful neurological exam. Neurocognitive testing was completed preoperatively and up to 1 week postoperatively to assess POD (3D-CAM) and POCD (Short Blessed Test). Time to first reliable neurological exam was 2 minutes longer in group A (9 min ± 4 min) compared to group B and group C (7 min ± 3 min; 7 min ± 4 min), although this was not statistically significant. In addition, extubation time was significantly longer in group A (11 min) compared to group B and group C (5 min; 6 min) (P = 0.03). 3D -CAM and Short Blessed Test data along with hemodynamics did not differ significantly between the groups. Time to first useful neurologic exam and hemodynamics did not differ between the groups. However, extubation time was significantly prolonged in patients who received propofol, but not dexmedetomidine, as part of their anesthetic for CEA. These findings are best verified in an adequately powered prospective randomized study.

Regioselective Synthesis of Multifunctional Allylic Amines; Access to Ambiphilic Aziridine Scaffolds.

We describe, for the first time, a highly regioselective hydrosilylation of propargylic amines. The reaction utilizes a PtCl2/XantPhos catalyst system to deliver hydrosilanes across the alkyne to afford multifunctional allylic amines in high yields. The reaction is tolerant to a wide variety of functional groups and provides high value intermediates with two distinct functional handles. The synthetic applicability of the reaction has been shown through the synthesis of diverse ambiphilic aziridines.

Determination of Moisture in Olive Oil: Rapid FT-NIR Spectroscopic Procedure Based on the Karl-Fischer Reference Method.

According to CODEX, moisture and volatile matter are olive oil quality parameters and the development of a rapid screening method for the determination of moisture is of interest. We recently demonstrated for the first time that the weak near-infrared (NIR) band near 5260 cm-1 is primarily attributed to a water O-H combination band. To determine the intensity of this band, we measured the peak-to-peak (p-p) height of its first derivative and generated exponential calibration curves for p-p height versus gravimetrically determined concentrations of spiked water in olive oils that had been purged of their initial moisture contents. To further optimize this univariate calibration method, calibration curves were generated in the present study based on plotting the moisture band first derivative p-p heights for neat olive oils (that were neither purged nor spiked) versus the moisture concentrations obtained by the Karl-Fischer (KF) primary reference method. To enhance the speed of FT-NIR data collection, measurements were carried in the transmission mode using disposable glass tubes. We also developed and compared a multivariate partial least squares approach to the univariate one. All the spectra were collected in two separate laboratories using two FT-NIR spectrometers of the same brand and model and no significant difference (p > 0.05) was found between the two laboratory determinations and the KF reference values at a 95% confidence interval. High accuracies were found with the two FT-NIR instruments used, as indicated by the low root mean squared error (RMSE, %) for predicted values obtained with the univariate procedure (RMSE = 0.008% and 0.010%) and the multivariate one, which yielded an even lower value (RMSE= 0.007% for both instruments). These results suggest that, once validated, the FT-NIR approach could potentially be a rapid substitute for the KF method.

Advances in biomarker development in acetaminophen toxicity.

Acetaminophen liver injury is the most common cause of acute liver injury in the United States and several other countries. Diagnosis of acetaminophen-induced acute liver injury in the clinic is challenging due to the lack of validated and specific biomarkers. The following chapter provides an overview of recent advances evaluating candidate biomarkers in development for acetaminophen acute liver injury. Relationships of biomarkers to mechanisms of acetaminophen toxicity and their potential role in confirming the diagnosis and/or predicting evolving toxicity are addressed.

Acetaminophen is both bronchodilatory and bronchoprotective in human precision cut lung slice airways.

Epidemiologic studies have demonstrated an association between acetaminophen (APAP) use and the development of asthma symptoms. However, few studies have examined relationships between APAP-induced signaling pathways associated with the development of asthma symptoms. We tested the hypothesis that acute APAP exposure causes airway hyper-responsiveness (AHR) in human airways. Precision cut lung slice (PCLS) airways from humans and mice were used to determine the effects of APAP on airway bronchoconstriction and bronchodilation and to assess APAP metabolism in lungs. APAP did not promote AHR in normal or asthmatic human airways ex vivo. Rather, high concentrations mildly bronchodilated airways pre-constricted with carbachol (CCh), histamine (His), or immunoglobulin E (IgE) cross-linking. Further, the addition of APAP prior to bronchoconstrictors protected the airways from constriction. Similarly, in vivo treatment of mice with APAP (200 mg/kg IP) resulted in reduced bronchoconstrictor responses in PCLS airways ex vivo. Finally, in both mouse and human PCLS airways, exposure to APAP generated only low amounts of APAP-protein adducts, indicating minimal drug metabolic activity in the tissues. These findings indicate that acute exposure to APAP does not initiate AHR, that high-dose APAP is protective against bronchoconstriction, and that APAP is a mild bronchodilator.

Effects of the Adulteration Technique on the Near-Infrared Detection of Melamine in Milk Powder.

The United States Pharmacopeial Convention has led an international collaborative project to develop a toolbox of screening methods and reference standards for the detection of milk powder adulteration. During the development of adulterated milk powder reference standards, blending methods used to combine melamine and milk had unanticipated strong effects on the near-infrared (NIR) spectrum of melamine. The prominent absorbance band at 1468 nm of melamine was retained when it was dry-blended with skim milk powder but disappeared in wet-blended mixtures, where spray-dried milk powder samples were prepared from solution. Analyses using polarized light microscopy, Raman spectroscopy, dielectric relaxation spectroscopy, X-ray diffraction, and mass spectrometry indicated that wet blending promoted reversible and early Maillard reactions with lactose that are responsible for differences in melamine NIR spectra between wet- and dry-blended samples. Targeted detection estimates based solely on dry-blended reference standards are likely to overestimate NIR detection capabilities in wet-blended samples as a result of previously overlooked matrix effects arising from changes in melamine hydrogen-bonding status, covalent complexation with lactose, and the lower but more homogeneous melamine local concentration distribution produced in wet-blended samples. Techniques used to incorporate potential adulterants can determine the suitability of milk reference standards for use with rapid detection methods.

An Immunoassay to Rapidly Measure Acetaminophen Protein Adducts Accurately Identifies Patients With Acute Liver Injury or Failure.

BACKGROUND & AIMS: A rapid and reliable point-of-care assay to detect acetaminophen protein adducts in the serum of patients with acute liver injury could improve diagnosis and management. AcetaSTAT is a competitive immunoassay used to measure acetaminophen protein adducts formed by toxic metabolites in serum samples from patients. We compared the accuracy of AcetaSTAT vs high-pressure liquid chromatography with electrochemical detection (HPLC-EC; a sensitive and specific quantitative analytic assay) to detect acetaminophen protein adducts. METHODS: We collected serum samples from 19 healthy individuals (no liver injury, no recent acetaminophen use), 29 patients without acetaminophen-associated acute liver injury, and 33 patients with acetaminophen-associated acute liver injury participating in the Acute Liver Failure Study Group registry. Each serum sample was analyzed by AcetaSTAT (reported as test band amplitude) and HPLC-EC (the reference standard). We also collected data on patient age, sex, weight, level of alanine aminotransferase on test day and peak values, concentration of acetaminophen, diagnoses (by site investigator and causality review committee), and outcome after 21 days. Differences between groups were analyzed using the Fisher exact test for categoric variables and the Kruskal-Wallis test or rank-sum test for continuous variables. RESULTS: AcetaSTAT discriminated between patients with and without acetaminophen-associated acute liver injury; the median AcetaSTAT test band amplitude for patients with acetaminophen-associated acute liver injury was 584 (range, 222-1027) vs 3678 (range, 394-8289) for those without (P < .001). AcetaSTAT identified patients with acetaminophen-associated acute liver injury with 100% sensitivity, 86.2% specificity, a positive predictive value of 89.2%, and a negative predictive value of 100%. Results from AcetaSTAT were positive in 4 subjects who received a causality review committee diagnosis of non-acetaminophen-associated acute liver injury; HPLC-EC and biochemical profiles were consistent with acetaminophen-associated acute liver injury in 3 of these cases. CONCLUSIONS: The competitive immunoassay AcetaSTAT shows a high degree of concordance with HPLC-EC results in identifying patients with acetaminophen-associated acute liver injury. This rapid and simple assay could increase early detection of this disorder and aid clinical management.

Cooperativity in CYP2E1 metabolism of acetaminophen and styrene mixtures.

Risk assessment for exposure to mixtures of drugs and pollutants relies heavily on in vitro characterization of their bioactivation and/or metabolism individually and extrapolation to mixtures assuming no interaction. Herein, we demonstrated that in vitro CYP2E1 metabolic activation of acetaminophen and styrene mixtures could not be explained through the Michaelis-Menten mechanism or any models relying on that premise. As a baseline for mixture studies with styrene, steady-state analysis of acetaminophen oxidation revealed a biphasic kinetic profile that was best described by negative cooperativity (Hill coefficient=0.72). The best-fit mechanism for this relationship involved two binding sites with differing affinities (Ks=830µM and Kss=32mM). Introduction of styrene inhibited that reaction less than predicted by simple competition and thus provided evidence for a cooperative mechanism within the mixture. Likewise, acetaminophen acted through a mixed-type inhibition mechanism to impact styrene epoxidation. In this case, acetaminophen competed with styrene for CYP2E1 (Ki=830µM and Ksi=180µM for catalytic and effector sites, respectively) and resulted in cooperative impacts on binding and catalysis. Based on modeling of in vivo clearance, cooperative interactions between acetaminophen and styrene resulted in profoundly increased styrene activation at low styrene exposure levels and therapeutic acetaminophen levels. Current Michaelis-Menten based toxicological models for mixtures such as styrene and acetaminophen would fail to detect this concentration-dependent relationship. Hence, future studies must assess the role of alternate CYP2E1 mechanisms in bioactivation of compounds to improve the accuracy of interpretations and predictions of toxicity.

Acetaminophen protein adduct formation following low-dose acetaminophen exposure: comparison of immediate-release vs extended-release formulations.

PURPOSE: Acetaminophen (APAP) protein adducts are a biomarker of APAP metabolism, reflecting oxidation of APAP and generation of the reactive metabolite N-acetyl-p-benzoquinone imine. High levels of adducts correspond to liver toxicity in patients with APAP-related acute liver failure. Adduct formation following low-dose exposure to APAP has not been well studied. APAP protein adducts were measured in blood samples collected from fasted individuals who participated in a crossover study of APAP (80 mg/kg) comparing extended release (ER) and immediate release (IR) formulations. METHODS: Adducts were quantified in all postdose blood samples using a validated high-performance liquid chromatography electrochemical detection (HPLC-EC) assay. RESULTS: Comparison of pharmacokinetic parameters for adducts did not reveal significant differences between ER and IR formulations, with one exception. Formation rates for adducts were faster for IR than the ER formulation (0.420 ± 0.157 vs. 0.203 ± 0.080 1/h), respectively. Maximum plasma concentrations (Cmax) of adducts for IR and ER were 0.108 (±0.020) and 0.100 (±0.028) nmol/ml serum, respectively, and were two orders of magnitude lower than adduct levels previously reported in adults with acute liver failure secondary to APAP. CONCLUSIONS: APAP protein adducts are rapidly formed following nontoxic ingestion of APAP at levels significantly lower than those associated with acute liver failure.

Mouse liver protein sulfhydryl depletion after acetaminophen exposure.

Acetaminophen (APAP)-induced liver injury is the leading cause of acute liver failure in many countries. This study determined the extent of liver protein sulfhydryl depletion not only in whole liver homogenate but also in the zonal pattern of sulfhydryl depletion within the liver lobule. A single oral gavage dose of 150 or 300 mg/kg APAP in B6C3F1 mice produced increased serum alanine aminotransferase levels, liver necrosis, and glutathione depletion in a dose-dependent manner. Free protein sulfhydryls were measured in liver protein homogenates by labeling with maleimide linked to a near infrared fluorescent dye followed by SDS-polyacrylamide gel electrophoresis. Global protein sulfhydryl levels were decreased significantly (48.4%) starting at 1 hour after the APAP dose and maintained at this reduced level through 24 hours. To visualize the specific hepatocytes that had reduced protein sulfhydryl levels, frozen liver sections were labeled with maleimide linked to horseradish peroxidase. The centrilobular areas exhibited dramatic decreases in free protein sulfhydryls while the periportal regions were essentially spared. These protein sulfhydryl-depleted regions correlated with areas exhibiting histopathologic injury and APAP binding to protein. The majority of protein sulfhydryl depletion was due to reversible oxidation since the global- and lobule-specific effects were essentially reversed when the samples were reduced with tris(2-carboxyethy)phosphine before maleimide labeling. These temporal and zonal pattern changes in protein sulfhydryl oxidation shed new light on the importance that changes in protein redox status might play in the pathogenesis of APAP hepatotoxicity.

Changes in mouse liver protein glutathionylation after acetaminophen exposure.

The role of protein glutathionylation in acetaminophen (APAP)-induced liver injury was investigated in this study. A single oral gavage dose of 150 or 300 mg/kg APAP in B6C3F1 mice produced increased serum alanine aminotransferase and aspartate aminotransferase levels and liver necrosis in a dose-dependent manner. The ratio of GSH to GSSG was decreased in a dose-dependent manner, suggesting that APAP produced a more oxidizing environment within the liver. Despite the increased oxidation state, the level of global protein glutathionylation was decreased at 1 h and continued to decline through 24 h. Immunohistochemical localization of glutathionylated proteins showed a complex dynamic change in the lobule zonation of glutathionylated proteins. At 1 h after APAP exposure, the level of glutathionylation decreased in the single layer of hepatocytes around the central veins but increased mildly in the remaining centrilobular hepatocytes. This increase correlated with the immunohistochemical localization of APAP covalently bound to protein. Thereafter, the level of glutathionylation decreased dramatically over time in the centrilobular regions with major decreases observed at 6 and 24 h. Despite the overall decreased glutathionylation, a layer of cells lying between the undamaged periportal region and the damaged centrilobular hepatocytes exhibited high levels of glutathionylation at 3 and 6 h in all samples and in some 24-h samples that had milder injury. These temporal and zonal pattern changes in protein glutathionylation after APAP exposure indicate that protein glutathionylation may play a role in protein homeostasis during APAP-induced hepatocellular injury.

A novel defensive mechanism against acetaminophen toxicity in the mouse lateral nasal gland: role of CYP2A5-mediated regulation of testosterone homeostasis and salivary androgen-binding protein expression.

To identify novel factors or mechanisms that are important for the resistance of tissues to chemical toxicity, we have determined the mechanisms underlying the previously observed increases in resistance to acetaminophen (APAP) toxicity in the lateral nasal gland (LNG) of the male Cyp2g1-null/Cyp2a5-low mouse. Initial studies established that Cyp2a5-null mice, but not a newly generated strain of Cyp2g1-null mice, were resistant to APAP toxicity in the LNG; therefore, subsequent studies were focused on the Cyp2a5-null mice. Compared with the wild-type (WT) male mouse, the Cyp2a5-null male mouse had intact capability to metabolize APAP to reactive intermediates in the LNG, as well as unaltered circulating levels of APAP, APAP-GSH, APAP-glucuronide, and APAP-sulfate. However, it displayed reduced tissue levels of APAP and APAP-GSH and increased tissue levels of testosterone and salivary androgen-binding protein (ABP) in the LNG. Furthermore, we found that ABP was able to compete with GSH and cellular proteins for adduction with reactive metabolites of APAP in vitro. The amounts of APAP-ABP adducts formed in vivo were greater, whereas the amounts of APAP adducts formed with other cellular proteins were substantially lower, in the LNG of APAP-treated male Cyp2a5-null mice compared with the LNG of APAP-treated male WT mice. We propose that through its critical role in testosterone metabolism, CYP2A5 regulates 1) the bioavailability of APAP and APAP-GSH (presumably through modulation of the rates of xenobiotic excretion from the LNG) and 2) the expression of ABP, which can quench reactive APAP metabolites and thereby spare critical cellular proteins from inactivation.

Acetaminophen-induced hepatotoxicity in mice occurs with inhibition of activity and nitration of mitochondrial manganese superoxide dismutase.

In overdose the analgesic/antipyretic acetaminophen (APAP) is hepatotoxic. Toxicity is mediated by initial hepatic metabolism to N-acetyl-p-benzoquinone imine (NAPQI). After low doses NAPQI is efficiently detoxified by GSH. However, in overdose GSH is depleted, NAPQI covalently binds to proteins as APAP adducts, and oxygen/nitrogen stress occurs. Toxicity is believed to occur by mitochondrial dysfunction. Manganese superoxide dismutase (MnSOD) inactivation by protein nitration has been reported to occur during other oxidant stress-mediated diseases. MnSOD is a critical mitochondrial antioxidant enzyme that prevents peroxynitrite formation within the mitochondria. To examine the role of MnSOD in APAP toxicity, mice were treated with 300 mg/kg APAP. GSH was significantly reduced by 65% at 0.5 h and remained reduced from 1 to 4 h. Serum alanine aminotransferase did not significantly increase until 4 h and was 2290 IU/liter at 6 h. MnSOD activity was significantly reduced by 50% at 1 and 2 h. At 1 h, GSH was significantly depleted by 62 and 80% at nontoxic doses of 50 and 100 mg/kg, respectively. No further GSH depletion occurred with hepatotoxic doses of 200 and 300 mg/kg APAP. A dose response decrease in MnSOD activity was observed for APAP at 100, 200, and 300 mg/kg. Immunoprecipitation of MnSOD from livers of APAP-treated mice followed by Western blot analysis revealed nitrated MnSOD. APAP-MnSOD adducts were not detected. Treatment of recombinant MnSOD with NAPQI did not produce APAP protein adducts. The data indicate that MnSOD inactivation by nitration is an early event in APAP-induced hepatic toxicity.

The proper use of acetaminophen.

Acetaminophen (N-acetyl-p-aminophenol, paracetamol [APAP])-induced acute liver failure is the most common cause of acute liver failure in adults. In children, APAP accounts for 25% of all cases of acute liver failure. The high mortality rate associated with this preventable condition makes it vital that paediatricians are aware of the potential adverse effects associated with this widely used drug. While APAP is generally considered to be safe when used as directed, its inclusion in multiple over-the-counter medications, as well as in prescription drugs, mandates that physicians promote and educate the general public about the proper use of acetaminophen in children.

Favorable Protonation of the (µ-edt)[Fe(2)(PMe(3))(4)(CO)(2)(H-terminal)](+) Hydrogenase Model Complex Over Its Bridging µ-H Counterpart: A Spectroscopic and DFT Study.

The mechanism of hydrogen production in [FeFe] hydrogenase remains elusive. However, a species featuring a terminal hydride bound to the distal Fe is thought to be the key intermediate leading to hydrogen production. In this study, density functional theory (DFT) calculations on the terminal (H-term) and bridging (µ-H) hydride isomers of (µ-edt)-[Fe(2)(PMe(3))(4)(CO)(2)H](+) are presented in order to understand the factors affecting their propensity for protonation. Relative to H-term, µ-H is 12.7 kcal/mol more stable, which contributes to its decreased reactivity towards an acid. Potential energy surface (PES) calculations for the reaction of the H-term isomer with 4-nitropyridinium, a proton source, further reveal a lower activation energy barrier (14.5 kcal/mol) for H-term than for µ-H (29 kcal/mol). Besides these energetic considerations, the H-term isomer displays a key molecular orbital (MO <139>) that has a relatively strong hydride (1s) contribution (23%), which is not present in the µ-H isomer. This indicates a potential orbital control of the reaction of the hydride complexes with acid. The lower activation energy barrier and this key MO together control the overall catalytic activity of (µ-edt)[Fe(2)(PMe(3))(4)(CO)(2)(H-term)](+). Lastly, Raman and IR spectroscopy were performed in order to probe the ν(Fe-H) stretching mode of the two isomers and their deuterated counterparts. A ν(Fe-H) stretching mode was observed for the µ-H complex at 1220 cm(-1). However, the corresponding mode is not observed for the less stable H-term isomer.

Expression of sulfotransferase isoform 1A1 (SULT1A1) in breast cancer cells significantly increases 4-hydroxytamoxifen-induced apoptosis.

Previously, we reported a strong association of the high activity SULT1A1*1 allele and overall survival of patients receiving tamoxifen therapy, indicating that sulfation of 4-hydroxytamoxifen (4-OHT) via SULT1A1 may contribute to the therapeutic efficacy of tamoxifen treatment. In most, but not all cases, sulfation is considered to be an elimination pathway; therefore we sought to define the biological mechanism by which increased sulfation of tamoxifen could provide a therapeutic benefit. We compared the antiproliferative and apoptotic responses between MCF7-SULT1A1 expressing cells and control MCF7 pcDNA3 cells when treated with 4-OHT. We observed a greater than 30% decrease in cell proliferation in MCF7-SULT1A1 expressing cells at physiological concentrations of 4-OHT, and significant cell death in SULT1A1-expressing cells treated with 2µM 4-OHT for 48 hours compared to control cells (p<0.05). Within 24 hours of drug treatment, an 80% increase in apoptosis in SULT1A1-expressing cells was apparent when compared to similarly treated cells that did not express SULT1A1. We also observed an increase in endonuclease G, the primary endonuclease expressed in ER-dependent breast cancer cells, which participates in caspaseindependent apoptosis. These data confirm that SULT1A1-mediated biotransformation of 4-OHT is important in the efficacy of 4-OHT cytotoxicity in breast tumors, and reveals a potential role for sulfated metabolites in the efficacy of tamoxifen therapy.